Quarterly Financial Data (Unaudited) - Selected Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Data (Unaudited)
Interest income	$ 42,471	$ 33,250	$ 33,489	$ 33,449	$ 35,378	$ 34,610	$ 31,980	$ 27,877	$ 142,659	$ 129,845	$ 106,911
Interest expense	3,242	2,625	2,573	2,407	2,318	2,159	1,816	1,529	10,847	7,822	5,387
Net interest income	39,229	30,625	30,916	31,042	33,060	32,451	30,164	26,348	131,812	122,023	101,524
Provision (credit) for loan losses	3,223	(576)	(740)	(1,061)	142	(425)	7,198	506	846	7,421	99
Net interest income after provision for loan losses	36,006	31,201	31,656	32,103	32,918	32,876	22,966	25,842	130,966	114,602	101,425
Noninterest income	2,393	2,618	2,765	2,468	2,393	2,206	2,780	2,195	10,244	9,574	9,612
Noninterest expense	30,626	17,909	18,445	17,918	16,941	17,728	24,862	15,990	84,898	75,521	60,738
Income before income taxes	7,773	15,910	15,976	16,653	18,370	17,354	884	12,047	56,312	48,655	50,299
Income tax expense	2,088	4,633	4,623	4,507	5,138	4,979	(31)	3,238	15,851	13,324	26,471
Net income	$ 5,685	$ 11,277	$ 11,353	$ 12,146	$ 13,232	$ 12,375	$ 915	$ 8,809	$ 40,461	$ 35,331	$ 23,828
Earnings per common share:
Basic (in dollars per share)	$ 0.10	$ 0.26	$ 0.26	$ 0.28	$ 0.31	$ 0.29	$ 0.02	$ 0.23	$ 0.87	$ 0.85	$ 0.63
Diluted (in dollars per share)	$ 0.10	$ 0.26	$ 0.26	$ 0.28	$ 0.30	$ 0.28	$ 0.02	$ 0.23	$ 0.84	$ 0.84	$ 0.62